Research On Contention Resolution Of Optical Burst Switching Networks

As the development of communication technology, existing networks can't meet the fast growth of Internet business requirements, which inspires the research on network transmission and switching technologies. Wavelength division multiplexing is to combine hundreds of gigabit channels into one fiber. Network transmission capacity is considerably improved by dense wavelength division multiplexing (DWDM) technology, specially. The growth of transmitting rate is already far beyond the current network switching capacity. The electronic switching system hasn't been appropriate for Internet development. Consequently, it is inevitable to solve this bottleneck by optical switching technology.There are three kinds of optical switching technology:optical circuit switching (OCS), optical packet switching (OPS) and optical burst switching (OBS). OBS combines advantages of OPS and OCS. OBS is a very promising optical switching technology for building the next generation optical Internet for which switches flexibly, overcomes the disadvantages of OPS and OCS and doesn't need optical devices.To improve the network efficiency, statistical multiplexing is used in OBS networks, which may cause burst data packet collisions. It is a key issue to reduce the number of contentions by efficient contention resolution in order to minimize the packet loss rate.Firstly, this thesis introduces the basic concept, development, applications and future of OBS technology. Then we describe the general network architecture and working principle of OBS networks. The key technologies related to the OBS networks are also discussed, such as, burst assembly, signaling protocol, channel scheduling, and contention resolution. Then, the reason of burst contention is analyzed, and these existing contention resolutions schemes including optical fiber delay line (FDL) buffers, wavelength conversion, deflection routing and burst segmentation are also discussed. On the basis, we present a channel grading contention resolution, and its performance is discussed in simulation by OPNET network simulation platform. We obtain packet lost rate and average processing delay curves under different channel configurations. The result shows that this scheme is a practical resolution which could support different service requirements and effectively manage the blance between the packet loss rate and average processing delay in OBS networks.